Retracting Rear Caliper Pistons

[andy110m]

Hi Guys,

I've just swapped the rear disks on my 2000 S4 avant. No problems getting the disk done but I really struggled to wind the pistons back in. I'm wondering if I'm missing something, or if the return is something that can go wrong.

I managed the off side but it was really tight. After a short time with it moving we got the new pads in. The problem was the near side that was alot easier to move but didn't retract. In the end we put the old pads back, we didn't get the room to get the new ones in.

I thought I'd post on here and see if some of you knowledgeable folk could tell me what my mate and I are missing, apart from mechanical talent obviously.

Thanks.

 

[yendall24]

the trick with these is to apply loads of preasure and turn very slowly i dont know why the speed that you turn the piston matters but it does i have found this a few times very slowly is the answer

 

[Broken Byzan]

I have also found pushing the piston out a bit more and a liberal spray of LUBE under the dust seal can help too. You will need to be careful you do not go too far and push the piston out, or too far to get the windy tool in place.

 

[andy110m]

So I need to push the piston in and twist it at the same time. Whats the best way of achieving that?

Thanks for all your help and advice guys

 

[Broken Byzan]

Have you not got a piston retracting tool?

thats what you need

 

[andy110m]

Ah I need a special tool. I used a piece of bar with 2 blobs of weld on, ground to engage the cut outs on the piston. My mate turned that while I had some big grips trying to force the piston in.

That worked on the off side but only limited success on the near side. The new pads would fit but only when lightly hammered in and that was no good because it would all bind up. We just couldn't get that last couple of mill.

what sort of money is the correct tool? You called it a windy tool, its powered by compressed air?

 

[Broken Byzan]

What you have will probably work with some ingenious G clampage and twist. Its a more pressure, less turn that seems to work.

I think it's just called a piston retracting tool, it has a tommy bar and a blank metal plate kinda like a pad that has a slot in it to allow the cetre bit to slot in to allow it tp apply pressure to the piston while the tommy bar bit is turned, around £18 iirc. Worth its weight in platinum IMHO

 

[raver100]

I used a small g-clamp and a pair of mole grips to turn the pad on the g-clamp worked just!

 

[sun and kath]

try i as did , i could not retract one of mine on the car.
undid brake pipe and placed in vice - job done.
lots of effort was needed, no way i would have doen it with the tools i had to hand on the car.

 

[CraigG]

Wouldnt jamming it in a vice like that damage the handbrake mechanism?